The program began in January 1955 when the Scientific Advisory Committee recommended an alternate approach to the ICBM.[1] In May 1955 the Air Material Command invited contractors to submit proposals and bids for the two stage alternate source ICBM. In September 1955 Martin was declared the contractor for the Titan missile. In early October the Air Force's Western Development Division was ordered to commence the Titan program.[1] The Titan was developed in parallel with the Atlas (SM-65/HGM-16) Intercontinental Ballistic Missile. The Air Force's goal in launching the Titan program was threefold: one, to serve as a backup should Atlas fail; two, to develop a large, two-stage missile with potentially superior performance; and third to introduce competition which the head of Ballistic Missile Division, Brigadier General Bernard Schriever, thought might spur the Atlas contractor to work harder[2] Martin was selected as the contractor for two reasons. First it proposed a superior organization.[3] Second was that Martin proposed a method of dealing with the problem of igniting a liquid fueled engine at high altitude.[4]

The Titan I was initially designated B-68 in the numbering sequence of bombers.[5] It was later designate SM-68; then in 1962 it was redesignated HGM-25A.

The previous strategic missile programs of the Air Force had been administered using the "single prime contractor concept" (later called the weapon system concept).[6] This had resulted in three badly botched programs; the programs of the Snark, Navaho and Rascal missiles had slipped an average of 5 years and had cost overruns of 300 per cent or more.[7] The Teapot Committee had been created to evaluate requirements for, and methods of accelerating the development of ballistic missiles. Applying the Teapot committee's recommendations to manage ballistic missile programs the Air Research and Development Command established the Western Development Division and Brigadier General Bernard Schriever was detailed to command it. Schriever devised an entirely new organization for program management. The Air Force was to act as "prime contractor," the Ramo-Woolridge Corporation was contracted to provide systems engineering and technical direction of all ballistic missiles. The airframe contractor also would assemble the sub-systems provided by other Air Force contractors.[8] This new organization was very controversial.[9]

The Titan, proposed as a fall-back in case the Atlas failed, was by December 1956 accepted as a "principal ingredient of the national ballistic missile force."[10] Almost from the beginning Titan was threatened with cancelation.[11] In response to claims that the Titan was redundant arguments were made that the Titan offered greater performance and growth potential than the Atlas. Suggestions were made that it could make a superior space launch vehicle.[12] The Titan program was under constant budgetary pressure. In the summer of 1957 budget cuts led Secretary of Defense Wilson to make major changes in the Titan production rate from the proposed seven per month to two a month, which effectively reduced the Titan to a research and development program.[13] On October 5, 1957 Americans woke to learn that the Soviet Union had put Sputnik, the first satellite, in orbit. The public and press were shocked. Americans suffered a crisis of confidence. The launch of Sputnik was often compared to Pearl Harbor.[14] The effect ended any talk of canceling Titan. Priority was restored.[15] 1958 saw increases in funding and plans for additional Titan squadrons.

Produced by the Glenn L. Martin Company (which became "The Martin Company" in 1957), Titan I was a two-stage, liquid-fueled missile with an effective range of 5,500 nautical miles (10,200 km). The first stage delivered 300,000 pounds (1,330 kN) of thrust, the second stage 80,000 pounds (356 kN). The fact that Titan I, like Atlas, burned RP-1 and LOX meant that the oxidizer had to be loaded onto the missile just before launch from an underground storage tank, and the missile raised above ground on the enormous elevator system, exposing the missile for some time before launch. The complexity of the system combined with its relatively slow reaction time – fifteen minutes to load, raise and launch the first missile, made it a less effective weapon system. Following the launch of the first missile the other two could be fired at 7-1/2 minute intervals.[16]

Titan I utilized radio-inertial command guidance. The inertial guidance system originally intended for the missile was instead eventually deployed in the Atlas E and F missiles.[17] Less than a year later the Air Force considered deploying the Titan I with an all-inertial guidance system but that change never occurred.[18] (The Atlas series was intended to be the first generation of American ICBMs and Titan II (as opposed to Titan I) was to be the second generation deployed). The Titan 1 was controlled by an autopilot which was informed of the missile's attitude by a rate gyro assembly consisting of 3 gyroscopes. During the first minute or two of the flight a pitch programmer put the missile on the correct path.[16] From that point the AN/GRW-5 guidance radar tracked a transmitter on the missile. The guidance radar fed missile position data to the AN/GSK-1 (Univac Athena) missile guidance computer in the Launch Control Center.[19] The guidance computer used the tracking data to generate instructions which were encoded and transmitted to the missile by the guidance radar. Guidance input/output between the guidance radar and guidance computer occurred 10 times a second.[20] Guidance commands continued for the stage 1 burn, the stage 2 burn and the vernier burn ensuring the missile was on the correct trajectory and terminating the vernier burn at the desired velocity. The last thing the guidance system did was to determine if the missile was on the right trajectory and pre-arm the warhead which then separated from the second stage.[16] In case of the failure of the guidance system at one site, the guidance system at another site could be used to guide the missiles of the site with the failure.[21]

Titan I also was the first true multi-stage (two or more stages) design. The Atlas missile had all three of its main rocket engines ignited at launch (two were jettisoned during flight) due to concerns about igniting rocket engines at high altitude and maintaining combustion stability.[22] Martin, in part, was selected as the contractor because it had "recognized the 'magnitude of the altitude of the altitude start problem' for the second stage and had a good suggestion for solving it."[4] Titan I's second-stage engines were reliable enough to be ignited at altitude, after separation from the first stage booster. The first stage, besides including heavy fuel tanks and engines, also had launch interface equipment and the launch pad thrust ring with it. When the first stage had finished consuming its propellant, it dropped away, thereby decreasing the mass of the vehicle. Titan I’s ability to jettison this mass prior to the ignition of the second stage meant that Titan I had a much greater total range (and a greater range per pound of second-stage fuel) than Atlas, even if the total fuel load of Atlas had been greater.[citation needed]

As North American Aviation's Rocketdyne Division was the only manufacture of large liquid propellent rocket engines the Air Force Western Development Division decided to develop a second source for them. Aerojet-General was selected to design and manufacture the engines for the Titan. Aerojet produced the excellent LR87-AJ-3 (booster) and LR91-AJ-3 (sustainer). George P. Sutton wrote "Aerojet's most successful set of large LPRE was that for the booster and sustainer stages of the versions of the Titan vehicle".[23]

The warhead of the Titan I was an AVCO Mk 4 re-entry vehicle containing a W38 thermonuclear bomb with a yield of 3.75 megatons which was fuzed for either air burst or contact burst. The Mk 4 RV also deployed penetration aids in the form of mylar balloons which replicated the radar signature of the Mk 4 RV.[24]

The Titan I was tested in a comprehensive test program prior to deployment. The testing consisted of Series I, which tested the first stage while Series III tested the complete missile (Series II had been cancelled).[25] From the first successful launch on 5 February 1959 with Titan-1 A3 through to 29 January 1962 Titan-1 M7. There were seven variants of the Titan I Research and Development missile: six A-types (four launched) seven B-types (two launched), six C-types (five launched), ten G-types (seven launched), 22 J-types (22 launched), four V-types (four launched), seven M-types (seven launched). 62 produced (49 launched and two exploded). They were tested and launched at Cape Canaveral Air Force Station from Launch Complexes LC15, LC16, LC19 and LC20.

The first four tests of the Titan I (the Lot A missiles) were carried out on February 6, February 25, April 3, and May 4, 1959, all with dummy second stages. The success of these initial flights left launch crews unprepared for the coming events. On August 14, the first attempt to fly a Lot B (all-up version with a live second stage but dummy warhead) ended in disaster when the missile was released from LC-19 before it had built up sufficient thrust. The pad umbilical sent a shutdown signal to the engines and the Titan fell back onto the pad and exploded.[26]

In December, the second attempt to launch a complete Titan ended in practically identical fashion when vibration tripped the range safety destruct package on the first stage of Missile C-3 one second after liftoff, leading to another pad explosion.[27] On February 2, 1960, Missile B-7 marked the first successful flight of a Titan with a live upper stage. On February 5, Missile C-4 failed at T+52 seconds when the guidance compartment collapsed, causing the RVX-3 reentry vehicle to separate.[28] The missile pitched down and the first stage LOX tank ruptured from aerodynamic loads, blowing the stage to pieces. After the first stage destroyed itself, the second stage separated and began engine ignition, sensing that normal staging had taken place. With no attitude control, it began tumbling end-over-end and quickly lost thrust. The stage plummeted into the Atlantic Ocean some 30–40 miles downrange. After the successful flight of Missile G-4 on February 24, Missile C-1's second stage failed to ignite on March 8 due to a stuck valve preventing the gas generator from starting.[29] A run of successful launches followed during the spring, but the first attempt at flying a Lot J (operational prototype missile) on July 1 went awry when a broken hydraulic line caused total loss of control within moments of liftoff.[30] The Titan began flying on a near horizontal plane before Range Safety issued the destruct command at T+11 seconds. The next launch at the end of the month (Missile J-4) suffered premature first stage shutdown and landed far short of its planned impact point. Cause of the failure was a LOX valve closing prematurely, which resulted in the rupture of a propellant duct and thrust termination. Missile J-6 on October 24 set a record by flying 6100 miles.

The string of failures during 1959-60 led to complaints from the Air Force that Martin-Marietta weren't taking the Titan project seriously (since it was just a backup to the primary Atlas ICBM program) and displayed an indifferent, careless attitude that resulted in easily avoidable failure modes such as Missile C-3's range safety command destruct system relays being placed in a vibration-prone area.[31][32]

In December, Missile V-2 was undergoing a flight readiness test in a silo at Vandenberg Air Force Base. The plan was to load the missile with propellant, raise it up to firing position, and then lower it back into the silo. Unfortunately, the silo elevator collapsed, causing the Titan to fall back down and explode. The blast was so violent that it ejected a service tower from inside the silo and launched it some distance into the air before coming back down.[33]

Although most of the Titan I's teething problems were worked out by 1961, the missile was already eclipsed not only by the Atlas, but by its own designated successor, the Titan II, a bigger, more powerful ICBM with storable hypergolic propellants. The launch pads at Cape Canaveral were quickly converted for the new vehicle and as Vandenberg lacked actual pads (only silos), the Titan I quickly found itself homeless. After a brief period as an operational ICBM, it was retired from service in 1965 when Defense Secretary Robert McNamara made the decision to phase out all first generation cryogenically-fueled missiles in favor of newer hypergolic and solid-fueled models. While decommissioned Atlas (and later Titan II) missiles were recycled and utilized for space launches, the Titan I inventory was simply scrapped.[34]

Titan-1 Strategic Missile (SM) production began during the final stages of the Research and Development program. A "Blue Suit" launch of SM-2 from Vandenberg AFB LC-395-A3 on 21 January 1962, the last development flight of M7 was from Cape Canaveral's LC-19 on 29 January 1962.[35] In total, 101 Titan-1 SMs were produced to be tested from underground silos at Vandenberg Air Force Base or stationed in silos in six squadrons of nine missiles each across Western America. Fifty-four missiles in silos in total, with one missile as a spare on standby at each squadron, bringing to 60 in service at any one time.

Titan was originally planned for a 1 X 10 (one control center with 10 launchers) "soft" site.[36] In mid-1958 it was decided that the American Bosh Arma all-inertial guidance system designed for Titan would, because production was insufficient, be assigned to Atlas and the Titan would switch to radio-inertial guidance.[37] The decision was made to deploy Titan squadrons in a "hardened" 3 X 3 (3 sites with one control center and 3 silos each) to reduce the number of guidance systems required.[36] (radio-inertial guided Atlas D squadrons were similarly sited).[38] The Titan I was first American ICBM based in underground silos, and it gave USAF managers, contractors and missile crews valuable experience building and working in vast complexes containing everything the missiles and crews needed for operation and survival. The complexes were composed of an Entry Portal, Control Center, Powerhouse, Terminal Room, two Antenna Silos for the ATHENA guidance radar antennas, and three launchers each composed of: three Equipment Terminals, three Propellant Terminals, and three missile Silos. All connected by an extensive network of Tunnels.[39] Both Antenna Terminals and all three Launchers were isolated with double door Blast Locks to ensure that if there was an explosion or the site was under attack, that only the exposed antenna and/or missile silo would be damaged.[40]

The Launch Crew was composed of a missile combat crew commander, missile launch officer (MLO), guidance electronics officer (GEO), Ballistic Missile analyst technician (BMAT), and two electrical power production technicians (EPPT).[41] There were also a cook and two Air Police.[42] During normal duty hours there was a Site Commander, Site Maintenance Officer, Site Chief, job controller/expediter, tool crib operator, power house chief, three pad chiefs, three assistant pad chiefs, another cook and more air police. There could be a number of electricians, plumbers, power production technicians, air conditioning technicians, and other specialist when maintenance was being performed.[42]

These early silos, however, had certain drawbacks. First, the missiles took about 15 minutes to fuel, and then, one at a time, had to be lifted to the surface on huge elevators for launching, which slowed their reaction time. Rapid launching was crucial to avoid possible destruction by incoming missiles, even though Titan complexes were designed to withstand nearby nuclear blasts. The missiles sites of a squadron were placed at least 17 (usually 20 to 30) miles apart so that a single nuclear weapon could not take out two sites.[43] The sites also had to be close enough that if a sites guidance system failed it could "handover" its missiles to another site of the squadron.[44][45]

The distance between the antenna silos and the most distant missile silo was between 1,000 and 1,300 feet (400 m). These were by far the most complex, extensive and expensive missile launch facilities ever deployed by the USAF.[46][47][48] Launching a missile required fueling it in its silo, and then raising the launcher and missile out of the silo on a massive elevator. Before each launch the guidance radar, which was periodically calibrated by acquiring a special target at a precisely known range and bearing,[49] had to acquire a radio on the missile (missile guidance set AN/DRW-18, AN/DRW-19, AN/DRW-20, AN/DRW-21, or AN/DRW-22.[50][51] When the missile was launched, the guidance radar tracked the missile and supplied precise velocity range and azimuth data to the guidance computer which then generated guidance corrections which were transmitted to the missile. Because of this the complex could only launch and track one missile at a time.

Although Titan I's two stages gave it true intercontinental range and foreshadowed future multistage rockets, its propellants were dangerous and hard to handle. Super-chilled liquid oxygen oxidizer had to be pumped aboard the missile just before launch, and complex equipment was required to store and move this liquid. RP-1 fuel also was pumped aboard just before launch.

In its brief career, six squadrons were equipped with the Titan I. Each squadron was deployed in a 3x3 configuration, which meant a total of nine missiles were divided into three launch sites in Colorado, Idaho, California, Washington state and South Dakota. Each missile site had three Titan I ICBM missiles ready to launch at any given time. See squadron article for location of launch sites.

When the storable-fueled Titan II and the solid-fueled Minuteman I were deployed in 1963, the Titan I and Atlas missiles became obsolete. They were retired from service as ICBMs in early 1965. The count as of 5 March 1965 (the final launch from Vandenberg Air Force Base (VAFB): 17 were launched from VAFB (September 1961 – March 1965); one was destroyed in Beale AFB Site 851-C1 silo explosion 24 May 1962; 54 were based in Silos with SAC by 20 January 1965; 29 were in storage SBAMA (three at VAFB, one at each Base, including an extra at Lowry = 9 and 20 in storage at SBAMA elsewhere), a total of 101 production SM vehicles. The 83 surplus missiles remained in inventory at Mira Loma AFS. SM-65 Atlas missiles had already been converted to satellite launchers in the early 1960s, and the Titan I's had about the same payload capacity as an Atlas. It did not make economic sense to refurbish the 83 remaining missiles as launch vehicles. About 33 were distributed to museums, parks and schools as static displays (see list below). The remaining 50 missiles were scrapped at Mira Loma AFS near San Bernardino, CA, the last was broken up in 1972, in accordance with the SALT-I Treaty of 1 February 1972.

There were attempts to find new uses for 15 of the Titan I complexes.[53] In early 1965 the San Bernardino Air Material Area devised means of preserving installed material.[54] By November 1965 the Air Force Logistics Command had determined that the cost of modifying the widely dispersed sites was prohibitive.[55] By Spring 1966 a number of possible uses and users had been identified. By May 6, 1966 the Air Force wanted to retain 5 Titan sites and the General Services Administration had earmarked 1 for possible use. The USAF removed equipment it had uses for, the rest was offered to other government agencies.[56] Eventually no sites were retained and all were salvaged. The chosen method was the Service and Salvage contract. This required the contractor removed the equipment the government wanted. Then the contractor was allowed to scrap any thing it wanted from what was left.[57] This accounts for the varied degree of salvage at the sites today. Most are sealed today, one in Colorado is easily entered also very unsafe.[58] One is open for tours.[59]

Most of the ATHENA guidance computers were given to universities. One is in the Smithsonian. One remained in use at Vandenberg AFB until it guided a last Thor-Agena launch in May 1972. It had guided over 400 missiles.[60]

On 6 September 1985 Strategic Defense Initiative (AKA "Star Wars" program), a scrapped Titan I Second Stage was used in a Missile Defense test. The MIRACL Near Infrared Laser, at White Sands Missile Range, NM was fired at a stationary Titan I second stage that was fixed to ground. The second stage burst and was destroyed by the laser blast. The second stage did not contain any fuel or oxidizer. It was pressurized with nitrogen gas to 60-psi. A follow-up test 6 days later was conducted on a scrapped Thor IRBM, its remnants reside at the SLC-10 Museum at Vandenberg AFB.

There should be 33 Static Titan 1 Strategic Missiles and two (plus five possible) Research and Development Missiles to account for (of these 22 have been positively identified by Serial Number, eight known but need to be identified) and three are unaccounted for, missing.[citation needed]

The Titan I was considered for use as the first missile to put a man in space. Two of the firms responding to an Air Force "Request for Proposal" for "Project 7969," an early USAF project to "Put a Man in Space Soonest (MISS)". Two of the four firms which responded, Martin and Avco, proposed using Titan I as the booster.[61][62]